pub fn convert_base(num_str: &str, to_base: u32) -> String {
    // TODO: 这里写逻辑
    let parts: Vec<_> = num_str.split("(").collect();
    let num = parts[0];
    let old_base: u32 = parts[1].trim_end_matches(")").parse().unwrap();

    let decimal_value = u32::from_str_radix(num, old_base).unwrap();
    
    let mut result = String::new();
    let mut v = decimal_value;

    while v > 0 {
        let digit = v % to_base;
        result.push_str(&format!("{:x}", digit));
        v /= to_base;
    }

    result.chars().rev().collect()
}
